Filter device and plasma processing apparatus

ABSTRACT

There is provided a filter device. In the filter device, a plurality of coils are arranged coaxially. Each of a plurality of wirings is electrically connected to one end of each of the coils. Each of a plurality of capacitors is connected between the other end of each of the coils and the ground. A housing is electrically grounded and configured to accommodate therein the coils. Further, each of the wirings at least partially extends into the housing and has a length that is adjustable in the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2018-091444 filed on May 10, 2018, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a filter device and a plasmaprocessing apparatus.

BACKGROUND

In manufacturing electronic devices, a plasma processing apparatus hasbeen widely used. The plasma processing apparatus includes a chamber, asupporting table, and a high frequency power source. The supportingtable is provided in an inner space of the chamber and is configured tosupport a substrate to be mounted thereon. The supporting table includesa lower electrode and an electrostatic chuck. The high frequency powersource is connected to the lower electrode.

In plasma processes performed by the plasma processing apparatus, it isrequired to control in-plane temperature distribution of the substrate.In order to control the in-plane temperature distribution of thesubstrate, a plurality of heaters is provided in the electrostaticchuck. Each of the heaters is connected to a heater controller through aplurality of power supply lines.

A high frequency power is supplied from the high frequency power sourceto the lower electrode of the supporting table. The high frequency powersupplied to the lower electrode may flow into the power supply lines.Thus, a plurality of filters is provided in the power supply lines inorder to cut off or attenuate the high frequency power flowing into thepower supply lines. Each of the filters includes a coil and a capacitoras described in Japanese Patent Application Publication No. 2014-99585.The filters are provided outside the chamber.

In the plasma processing apparatus, a plurality of high frequency powershaving different frequencies may be supplied to the lower electrode.When the plurality of high frequency powers are used, the filter deviceneeds to cut off or attenuate each of the high frequency powers.Therefore, the filter device is required to be able to control animpedance of a high frequency power having a higher frequency among theplurality of high frequency powers. In other words, the filter deviceneeds to be able to control an impedance at a desired frequency.

SUMMARY

In accordance with an embodiment of the present disclosure, there isprovided a filter device including: a plurality of coils arrangedcoaxially; a plurality of wirings, each of which is electricallyconnected to one end of each of the coils; a plurality of capacitors,each of which is connected between the other end of each of the coilsand the ground; and a housing electrically grounded and configured toaccommodate therein the coils. Further, each of the wirings at leastpartially extends into the housing and has a length that is adjustablein the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present disclosure will become apparentfrom the following description of embodiments, given in conjunction withthe accompanying drawings, in which:

FIG. 1 schematically shows a plasma processing apparatus according to anembodiment;

FIG. 2 is an enlarged cross-sectional view of a supporting table of theplasma processing apparatus shown in FIG. 1;

FIG. 3 shows a circuit configuration of a plurality of filters of theplasma processing apparatus shown in FIG. 1 together with a plurality ofheaters and a heater controller;

FIG. 4 is a perspective view of a plurality of coils of a filter deviceaccording to the embodiment;

FIG. 5 is a partial perspective view of the coils shown in FIG. 4;

FIG. 6 is an enlarged perspective view showing a part of the coils shownin FIG. 4;

FIG. 7 schematically shows an electrical configuration for electricallyconnecting the coils of the filter device to a plurality of terminals ofan electrostatic chuck in the plasma processing apparatus shown in FIG.1;

FIG. 8 is a plan view of a bottom surface of the electrostatic chuck ofthe plasma processing apparatus shown in FIG. 1;

FIG. 9 is a plan view of a bottom surface of a lower electrode of theplasma processing apparatus shown in FIG. 1;

FIG. 10 is a plan view showing a plurality of members for electricallyconnecting the coils of the filter device to the terminals of theelectrostatic chuck in the plasma processing apparatus shown in FIG. 1;

FIG. 11 schematically shows the plasma processing apparatus according tothe embodiment;

FIG. 12 is a cross sectional view showing a wiring of the filter deviceaccording to one embodiment;

FIG. 13A is a graph showing frequency characteristics of an impedanceobtained in a first simulation and a second simulation;

FIG. 13B is a graph showing frequency characteristics of an impedanceobtained in the first simulation and a third simulation; and

FIG. 13C is a graph showing frequency characteristics of an impedanceobtained in the first simulation and a fourth simulation.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings. Like reference numerals will be given to likeor corresponding parts throughout the drawings.

FIG. 1 schematically shows a plasma processing apparatus according to anembodiment. FIG. 1 shows a cross-sectional view of the plasma processingapparatus according to an embodiment. The plasma processing apparatus 1shown in FIG. 1 is a capacitively coupled plasma processing apparatus.

The plasma processing apparatus 1 includes a chamber 10. The chamber 10has an inner space 10 s. The chamber 10 includes a chamber body 12. Thechamber body 12 has a substantially cylindrical shape. The inner space10 s is provided in the chamber body 12. The chamber body 12 is made of,e.g., aluminum. The chamber body 12 is frame-grounded. A plasmaresistant film is formed on an inner wall surface of the chamber body12. The inner wall surface of the chamber body 12 defines the innerspace 10 s. The plasma resistant film may be a film formed by anodicoxidation treatment or a ceramic film made of, e.g., yttrium oxide.

An opening 12 p is formed at a sidewall of the chamber body 12. Asubstrate W is transferred between the inner space 10 s and the outsideof the chamber 10 through the opening 12 p. The opening 12 p can beopened and closed by a gate opening 12 p. The gate valve 12 g isprovided along the sidewall of the chamber body 12. The substrate W is adisc-shaped plate made of, e.g., silicon.

The plasma processing apparatus 1 further includes a supporting table14. The supporting table 14 is provided in the inner space 10 s. Thesubstrate W is mounted on the supporting table 14. The supporting table14 is configured to support the substrate W in the inner space 10 s. Thesupporting table 14 is mounted on and supported by a supporting part 15.The supporting part 15 extends upward from the bottom portion of thechamber body 12.

A member 16, a member 17, and a baffle plate 18 are provided around thesupporting table 14 and the supporting part 15. The member 16 has acylindrical shape and is made of a conductor. The member 16 extendsupward from the bottom portion of the chamber body 12 along an outerperipheral surface of the supporting part 15. The member 17 has asubstantially annular plate shape and is made of an insulator such asquartz. The member 17 is provided above the member 16. A focus ring FRis provided on the member 17 to surround a peripheral edge of thesubstrate W mounted on the supporting table 14.

The baffle plate 18 has a substantially annular plate shape. The baffleplate 18 is formed by coating ceramic such as yttrium oxide on analuminum base material, for example. A plurality of through-holes isformed in the baffle plate 18. An inner peripheral portion of the baffleplate 18 is arranged between the member 16 and the member 17. The baffleplate 18 extends from the inner peripheral portion thereof to thesidewall of the chamber body 12. Below the baffle plate 18, a gasexhaust (GE) unit 20 is connected to the bottom portion of the chamberbody 12. The gas exhaust unit 20 includes a pressure controller such asan automatic pressure control valve, and a vacuum pump such as a turbomolecular pump. The gas exhaust unit 20 is configured to decrease apressure to the inner space 10 s.

The plasma processing apparatus 1 further includes an upper electrode30. The upper electrode 30 is provided above the supporting table 14.The upper electrode 30 blocks an upper opening of the chamber body 12 incooperation with a member 32. The member 32 has an insulating property.The upper electrode 30 is held at an upper portion of the chamber body12 through the member 32. The potential of the upper electrode 30 is setto the ground potential when a first high frequency power source to bedescribed later is electrically connected to a lower electrode of thesupporting table 14.

The upper electrode 30 includes a ceiling plate 34 and a holder 36. Abottom surface of the ceiling plate 34 faces the inner space 10 s. Theceiling plate 34 is provided with a plurality of gas injection holes 34a. The gas injection holes 34 a penetrate through the ceiling plate 34in a plate thickness direction (vertical direction). The ceiling plate34 is made of, e.g., silicon, but is not limited thereto. Alternatively,the ceiling plate 34 may be obtained by forming a plasma resistant filmon a surface of an aluminum base material. The plasma resistant film maybe a film formed by anodic oxidation treatment or a ceramic film madeof, e.g., yttrium oxide.

The holder 36 is configured to detachably hold the ceiling plate 34. Theholder 36 may be made of a conductive material such as aluminum. A gasdiffusion space 36 a is formed in the holder 36. A plurality of gasholes 36 b extends downward from the gas diffusion space 36 a. The gasholes 36 b communicate with the respective gas injection holes 34 a. Agas inlet port 36 c is formed at the holder 36. The gas inlet port 36 cis connected to the gas diffusion space 36 a. Further, the gas inletport 36 c is connected to a gas source group (GS) 40 through a valvegroup (VG) 41, a flow rate controller (FRC) group 42, and a valve group(VG) 43.

The gas source group 40 includes a plurality of gas sources. Each of thevalve group 41 and the valve group 43 includes a plurality of valves.The flow rate controller group 42 includes a plurality of flow ratecontrollers. Each of the flow rate controllers of the flow ratecontroller group 42 is a mass flow controller or a pressure control typeflow controller. The gas sources of the gas source group 40 areconnected to the gas inlet port 36 c through the valves of the valvegroup 41 and the valve group 43, and the flow rate controllers of theflow rate controller group 42, respectively. The plasma processingapparatus 1 is configured to supply gases from one or more gas sourcesselected among the plurality of gas sources of the gas source group 40to the inner space 10 s at individually controlled flow rates.

The plasma processing apparatus 1 further includes a control unit MC.The control unit MC is a computer including a processor, a storagedevice, an input device, a display device and the like, and controls therespective components of the plasma processing apparatus 1. A controlprogram and recipe data are stored in the storage device of the controlunit MC. The control unit MC executes the control program and controlsthe respective components of the plasma processing apparatus 1 based onthe recipe data. In the plasma processing apparatus 1, a processspecified by the recipe data is performed under the control of thecontrol unit MC.

Hereinafter, the supporting table 14 and the components of thesupporting table 14 of the plasma processing apparatus 1 will bedescribed in detail with reference to FIGS. 1 and 2. FIG. 2 is anenlarged cross-sectional view of the supporting table of the plasmaprocessing apparatus shown in FIG. 1. As shown in FIGS. 1 and 2, thesupporting table 14 includes a lower electrode 50 and an electrostaticchuck 52. In one embodiment, the supporting table 14 further includes aconductive member 54.

The lower electrode 50 has a substantially disc shape and is made of aconductor such as aluminum. A flow path 50 f is formed in the lowerelectrode 50. A heat exchange medium (e.g., a coolant) is supplied tothe flow path 50 f from a chiller unit provided outside the chamber 10.The heat exchange medium supplied to the flow path 50 f is returned tothe chiller unit. The lower electrode 50 is provided on the conductivemember 54.

The conductive member 54 is made of a conductor, e.g., aluminum. Theconductive member 54 is electrically connected to the lower electrode50. The conductive member 54 is formed in a substantially annular plateshape and has a hollow inner space. The conductive member 54, the lowerelectrode 50, and the electrostatic chuck 52 have a common central axis(hereinafter, referred to as “axis AX”). The axis AX is also the centralaxis of the chamber 10.

As shown in FIG. 1, in one embodiment, the plasma processing apparatus 1further includes a first high frequency power source 61 and a secondhigh frequency power source 62. The first high frequency power source 61and the second high frequency power source 62 are provided outside thechamber 10. The first high frequency power source 61 and the second highfrequency power source 62 are electrically connected to the lowerelectrode 50 through a power feeding unit 65. The power feeding unit 65has a columnar shape or a cylindrical shape. The power feeding unit 65extends downward from the bottom portion of the lower electrode 50. Inone embodiment, one end of the power feeding unit 65 is connected to theconductive member 54 and is electrically connected to the lowerelectrode 50 through the conductive member 54.

The first high frequency power source 61 mainly generates a first highfrequency power that contributes to plasma generation. The frequency ofthe first high frequency power is, e.g., 40.68 MHz or 100 MHz. The firsthigh frequency power source 61 is electrically connected to the lowerelectrode 50 through a matching unit (MU) 63 and the power feeding unit65. The matching unit 63 has a circuit configured to match an outputimpedance of the first high frequency power source 61 and an impedanceof a load side. The first high frequency power source 61 may beconnected to the upper electrode 30 through the matching unit 63.

The second high frequency power source 62 mainly outputs a second highfrequency power that contributes to attraction of ions to the substrateW. The frequency of the second high frequency power is, e.g., 13.56 MHz,that is lower than the frequency of the first high frequency power. Thesecond high frequency power source 62 is electrically connected to thelower electrode 50 through a matching unit (MU) 64 and the power feedingunit 65. The matching unit 64 has a circuit configured to match anoutput impedance of the second high frequency power source 62 and theimpedance of the load side.

The plasma processing apparatus 1 further includes a conductor pipe 66.The conductor pipe 66 is made of a conductor such as aluminum and has asubstantially cylindrical shape. The conductor pipe 66 extends tosurround the power feeding unit 65 outside the chamber 10. The conductorpipe 66 is connected to the bottom portion of the chamber body 12. Theconductor pipe 66 is electrically connected to the chamber body 12.Therefore, the conductor pipe 66 is grounded. The power feeding unit 65and the conductor pipe 66 have the axis AX as the central axis thereof.

As shown in FIGS. 1 and 2, the electrostatic chuck 52 is provided on thelower electrode 50. The electrostatic chuck 52 is configured to hold thesubstrate W mounted thereon. The electrostatic chuck 52 has asubstantially disc shape and has a layer made of an insulator such asceramics. The electrostatic chuck 52 further has an electrode 52 a as aninner layer of the insulator layer. A power supply DCS is connected tothe electrode 52 a through a switch SW (see FIG. 1). When a voltage(e.g., DC voltage) from the power supply DCS is applied to the electrode52 a, an electrostatic attractive force is generated between theelectrostatic chuck 52 and the substrate W. By generating theelectrostatic attractive force, the substrate W is attracted to and heldon the electrostatic chuck 52.

As shown in FIG. 2, the electrostatic chuck 52 includes a centralportion 52 c and a peripheral portion 52 p. The central portion 52 cintersects with the axis AX. The substrate W is mounted on an uppersurface of the central portion 52 c. The peripheral portion 52 p extendsin a circumferential direction from the outer side of the centralportion 52 c. In one embodiment, a thickness of the peripheral portion52 p is thinner than that of the central portion 52 c, and an uppersurface of the peripheral portion 52 p extends at a position lower thanthe upper surface of the central portion 52 c. A focus ring FR isdisposed on the peripheral portion 52 p and the member 17 to surroundthe edge of the substrate W.

A plurality of heaters HT is provided in the electrostatic chuck 52.Each of the heaters HT may be a resistance heating element. In oneexample, the electrostatic chuck 52 has a plurality of concentric zoneswith the axis AX, and one or more heaters HT are provided in each of theconcentric zones. The temperature of the substrate W mounted on thesupporting table 14 is controlled by the heaters HT and/or the heatexchange medium supplied to the flow path 50 f. In the supporting table14, a gas line for supplying a heat transfer gas such as He gas to a gapbetween the substrate W and the electrostatic chuck 52 may be provided.

In one embodiment, a plurality of terminals 52 t is provided on thebottom surface of the peripheral portion 52 p. Each of the terminals 52t is electrically connected to a corresponding one of the heaters HT.Each of the terminals 52 t and the heater corresponding thereto areconnected through an internal wiring in the electrostatic chuck 52.

The power for driving the heaters HT is supplied from a heatercontroller HC (see FIG. 1). The heater controller HC includes a heaterpower supply and is configured to individually supply power (AC output)to the heaters HT. In order to supply the power from the heatercontroller HC to the heaters HT, the plasma processing apparatus 1includes a plurality of power supply lines 70. Through the power supplylines 70, the power is supplied from the heater controller HC to theheaters HT. The plasma processing apparatus 1 further includes a filterdevice FD. The filter device FD is configured to prevent a highfrequency power from flowing into the heater controller HC through thepower supply lines 70. The filter device FD has a plurality of filtersFT.

FIG. 3 shows a circuit configuration of the filters of the plasmaprocessing apparatus shown in FIG. 1 together with the heaters and theheater controller. Hereinafter, the description will be explained withreference to FIGS. 1 to 3. The heaters HT are connected to the heatercontroller HC through the power supply lines 70, respectively, asdescribed above. The power supply lines 70 include a plurality of powersupply line pairs. As shown in FIG. 3, each of the power supply linepairs includes a power supply line 70 a and a power supply line 70 b.Each of the heaters HT is electrically connected with the heatercontroller HC through one power supply line pair, i.e., the power supplyline 70 a and the power supply line 70 b.

The filter device FD is provided outside the chamber 10. The filterdevice FD includes a plurality of coils 80, a plurality of capacitors82, a plurality of wirings 83, and a housing 84. Each of the coils 80has one end and the other end. Each of the wirings 83 is electricallyconnected to one end of each of the coils 80. Each of the wirings 83electrically connects each of the coils 80 with a heater correspondingthereto among the heaters HT. The other end of each of the coils 80 isconnected to the heater controller HC. One ends of the capacitors 82 areelectrically connected to the other ends of the coils 80, respectively.The other end of each of the capacitors 82 is electrically connected tothe ground.

The filter device FD includes a plurality of filters FT. Each of thefilters FT includes one coil among the coils 80 and one capacitorconnected the corresponding one coil among the capacitors 82. One coilamong the coils 80 and a plurality of wirings connected to thecorresponding one coil among the wirings 83 form a part of each of thepower supply lines 70.

The coils 80 are accommodated in the housing 84. At least a part of eachof the wirings 83 extends within the housing 84. In the examples ofFIGS. 1 and 2, the wirings 83 are accommodated in the housing 84. Asshown in FIGS. 1 and 2, the capacitors 82 are accommodated in thehousing 84 to be positioned below the coils 80.

The housing 84 is a cylindrical container. The housing 84 is made of aconductor. The housing 84 is electrically grounded. The coil 80 of eachfilter FT and the housing 84 constitute a distributed constant line. Inother words, each of the filters FT has impedance frequencycharacteristic including a plurality of resonance frequencies.

An upper end of the housing 84 may be fixed to the bottom portion of thechamber body 12. Therefore, the filter device FD may be provideddirectly below the chamber 10. In one embodiment, the housing 84includes a main body 84 a and a bottom lid 84 b. The main body 84 a hasa cylindrical shape. The bottom lid 84 b is attached to a lower end ofthe main body 84 a to block an opening at the lower end of the main body84 a.

Hereinafter, the coils 80 will be described in detail. FIG. 4 is aperspective view of the coils of the filter device according to anembodiment. FIG. 5 is a partial perspective view of the coils shown inFIG. 4. FIG. 6 is an enlarged perspective view showing a part of thecoils shown in FIG. 4. Each of the coils 80 may be an air-core coil. Thecoils 80 are arranged coaxially with a central axis AXC. The centralaxis AXC extends in a vertical direction. Each of the coils 80 has aconductor and a coating film covering the conductor. The coating film ismade of an insulating material. The coating film may be made of a resinsuch as polyetheretherketone (PEEK) or polyamideimide. In oneembodiment, the coating film of each coil 80 may have a thickness of 0.1mm or less.

Each of the coils 80 has lead lines 80 a and 80 b, and a winding portion80 w. The winding portion 80 w extends in a spiral shape around thecentral axis AXC and has a plurality of turns. The lead lines 80 a and80 b extend along an axial direction Z of the central axis AXC. The leadline 80 a extends from one end of the winding portion 80 w, and the leadline 80 b extends from the other end of the winding portion 80 w. Theother end of the winding portion 80 w is the end of the winding portion80 w on the side of the capacitor 82 corresponding thereto.

Groups of the coils 80 constitute a coil assembly CA. The coil assemblyCA includes a plurality of coil groups CG. In other words, the coils 80constitute a plurality of coil groups CG. The number of the coil groupsCG may be two or more. In the examples shown in FIGS. 4 to 6, the coilgroups CG include coil groups CG1, CG2, CG3, CG4 and CG5. Each of thecoil groups CG includes two or more coils 80. The number of the coils 80included in each of the coil groups CG may be two or more. In theexamples shown in FIGS. 4 to 6, the coil group CG1 includes eight coils80, the coil group CG2 includes nine coils 80, the coil group CG3includes nine coils 80, the coil group CG4 includes ten coils 80, andthe coil group CG5 includes eleven coils 80.

In the two or more coils 80 of each of the coil groups CG, therespective winding portions 80 w extend in a spiral shape around thecentral axis AXC and are arranged sequentially and repeatedly in theaxial direction Z. In other words, the winding portions 80 w of the twoor more coils 80 of each of the coil groups CG are arranged in multiplelayers along the axial direction Z and provided in a spiral shape aroundthe central axis AXC. In one embodiment, in each of the coil groups CG,a distance of the axial gap between conductors of adjacent turns in theaxial direction Z may be 0.2 mm or less.

The winding portions 80 w of the two or more coils 80 of each coil groupCG have the common central axis AXC and the same inner diameter and thesame outer diameter. The winding portions 80 w of the coils 80 have thesame cross sectional shape, e.g., a flat rectangular cross sectionalshape.

The coil groups CG are coaxially provided to have the common centralaxis AXC. In the examples shown in FIGS. 4 to 6, the coil groups CG1 toCG5 are arranged coaxially. Further, in the examples shown in FIGS. 4 to6, the coil group CG1 is provided at the inner side of the coil groupCG2, the coil group CG2 is provided at the inner side of the coil groupCG3, the coil group CG3 is provided at the inner side of the coil groupCG4, and the coil group CG4 is provided at the inner side of the coilgroup CG5.

The outer diameter of the winding portions 80 w of one of the twoadjacent coil groups in a radial direction relative to the central axisAXC is smaller than the inner diameter of the winding portions 80 w ofthe other one of the two adjacent coil groups. In the examples shown inFIGS. 4 to 6, the outer diameter of the winding portions 80 w of each ofthe two or more coils 80 included in the coil group CG1 is smaller thanthe inner diameter of the winding portions 80 w of each of the two ormore coils 80 included in the coil group CG2. The outer diameter of thewinding portions 80 w of each of the two or more coils 80 included inthe coil group CG2 is smaller than the inner diameter of the windingportions 80 w of each of the two or more coils 80 included in the coilgroup CG3. The outer diameter of the winding portions 80 w of each ofthe two or more coils 80 included in the coil group CG3 is smaller thanthe inner diameter of the winding portions 80 w of each of the two ormore coils 80 included in the coil group CG4. The outer diameter of thewinding portions 80 w of each of the two or more coils 80 included inthe coil group CG4 is smaller than the inner diameter of the windingportions 80 w of each of the two or more coils 80 included in the coilgroup CGS.

A pitch between turns of each of the two or more coils 80 of a firstcoil group of the coil groups CG is greater than a pitch between turnsof each of the two or more coils 80 of a second coil group disposed atan inner side of the first coil group. In the examples shown in FIGS. 4to 6, a pitch between turns of each of the coils 80 of the coil groupCG5 is greater than a pitch between turns of each of the coils 80 of thecoil group CG4. A pitch between turns of each of the coils 80 of thecoil group CG4 is greater than a pitch between turns of each of thecoils 80 of the coil group CG3. A pitch between turns of each of thecoils 80 of the coil group CG3 is greater than a pitch between turns ofeach of the coils 80 of the coil group CG2. A pitch between turns ofeach of the coils 80 of the coil group CG2 is greater than a pitchbetween turns of each of the coils 80 of the coil group CG1. In oneembodiment, the pitch between turns of each of the coils 80 is set suchthat inductances of the coils 80 become substantially the same.

When a plurality of coils is simply arranged in parallel, the impedancesof the filters are decreased. However, with the configuration of thefilter device FD in the present embodiment, the decrease in theimpedance is suppressed by the coupling between the coils 80. Inaddition, an inductance difference between the coils 80 is decreasedbecause the pitch between the turns of each of the two or more coils ofthe outer coil group is greater than the pitch between the turns of eachof the two or more coils of the inner coil group. Therefore, thedifference in frequency characteristic of the impedance of the filtersFT is reduced.

In one embodiment, the coils 80 have substantially the same coil length.The coil length indicates a length in the axial direction Z between oneend and the other end of the winding portion 80 w of each of the coils80. In one embodiment, a difference in length between the coil havingthe maximum coil length and the coil having the minimum coil lengthamong the coils 80 is 3% or less of the minimum coil length. Inaccordance with these embodiments, the difference In the frequencycharacteristics of the impedance of the filters FT is further reduced.

In one embodiment, the lead lines 80 a of the two or more coils 80 ofeach of the coil groups CG are provided at equal intervals in thecircumferential direction about the central axis AXC. In accordance withthe embodiment, the difference in the frequency characteristics of theimpedances of the filters FT is further reduced.

In one embodiment, a distance in the radial direction of the coil groupsCG, i.e., a distance of a radial gap between any two adjacent coilgroups in the radial direction about the central axis AXC, is 1.5 mm orless. In the present embodiment, the difference in the frequencycharacteristics of the impedances of the filters FT is further reduced.

In one embodiment, an inner diameter of the two or more coils 80 of theoutermost coil group among the coil groups CG is 1.83 times or less thanan inner diameter of the two or more coils of the innermost coil groupamong the coil groups CG. In the examples shown in FIG. 4 to 6, theinner diameter of each of the coils 80 of the coil group CGS is 1.83times or less than the inner diameter of each of the coils 80 of thecoil group CG1. In accordance with the present embodiment, thedifference in the frequency characteristics of the impedances of theplurality of filters FT is further reduced.

As described above, the filter device FD having the coils 80 is providedoutside the chamber 10. In one embodiment, the coil groups CG arearranged coaxially with the central axis AXC to surround the conductorpipe 66 at a position directly below the chamber 10. In a state wherethe coil groups CG are arranged at the position directly below thechamber 10, the central axis AXC coincides with the axis AX.

As shown in FIG. 3, the plasma processing apparatus 1 further includes aplurality of wirings 72. Each of the wirings 72 forms a part of each ofthe power supply lines 70. The wirings 72 are electrically connected tothe wirings 83, respectively. In other words, the wirings 83electrically connect the coils 80 provided outside the chamber 10 withthe terminals 52 t of the electrostatic chuck 52 through the wirings 72.Hereinafter, the wirings 72 will be described in detail with referenceto FIGS. 7 to 10 together with FIGS. 1 and 2. FIG. 7 schematically showsan electrical configuration for electrically connecting the coils of thefilter device to the terminals of the electrostatic chuck in the plasmaprocessing apparatus shown in FIG. 1. FIG. 8 is a plan view of thebottom surface of the electrostatic chuck of the plasma processingapparatus shown in FIG. 1. FIG. 9 is a plan view of the bottom surfaceof the lower electrode of the plasma processing apparatus shown inFIG. 1. FIG. 10 is a plan view showing a plurality of members forelectrically connecting the coils of the filter device to the terminalsof the electrostatic chuck in the plasma processing apparatus shown inFIG. 1.

As shown in FIG. 8, in one embodiment, the terminals 52 t are arrangedat the peripheral portion 52 p of the electrostatic chuck 52. Theterminals 52 t are arranged along the bottom surface of the peripheralportion 52 p. The terminals 52 t constitute a plurality of terminalgroups 52 g. Each of the terminal groups 52 g includes several terminals52 t. The terminal groups 52 g are arranged at equal intervals in theentire circumference of the peripheral portion 52 p. In one example, asshown in FIG. 8, the terminals 52 t constitute twelve terminal groups 52g. Each of the twelve terminal groups 52 g includes four terminals 52 t.

As shown in FIG. 9, the lower electrode 50 has a central portion 50 cand a peripheral portion 50 p. The central portion 52 c of theelectrostatic chuck 52 is provided on the central portion 50 c of thelower electrode 50. The peripheral portion 52 p of the electrostaticchuck 52 is provided on the peripheral portion 50 p of the lowerelectrode 50. Multiple through-holes are formed in the peripheralportion 50 p of the lower electrode 50. The upper ends of thethrough-holes of the peripheral portion 50 p are arranged to faceregions in the peripheral portion 52 p in which the terminal groups 52 gare provided. Multiple electrical connectors 73 are provided in thethrough-holes of the peripheral portion 50 p. The number of terminalsincluded in each of the electrical connectors 73 is equal to the numberof the terminals 52 t included in a corresponding one of the terminalgroups 52 g. The terminals of the electrical connectors 73 are connectedto the terminals 52 t, respectively.

As shown in FIG. 2, multiple electrical connectors 74 are provided inthe conductive member 54 to be positioned directly below the electricalconnectors 73. The electrical connectors 74 are connected to theelectrical connectors 73 corresponding thereto. Each of the electricalconnectors 74 has the same number of terminals as the corresponding oneof the electrical connectors 73. The terminals of the electricalconnectors 74 are connected to the terminals 52 t through the terminalsof the electrical connectors 73, respectively.

As shown in FIGS. 2 and 7, the lead lines 80 a of the coils 80 areconnected to a circuit board 85. The circuit board 85 is disposed abovethe coils 80. The circuit board 85 is disposed in the housing 84. Thecircuit board 85 has an annular plate shape to extend about the axis AX.Multiple wirings are formed on the circuit board 85. The wirings of thecircuit board 85 are connected to the lead lines 80 a of the coils 80,respectively. The wirings 83 are connected to the wirings of the circuitboard 85, respectively.

The wirings 83 are connected to multiple first electrical connectors 86.The first electrical connectors are disposed above the circuit board 85.The first electrical connectors 86 extend from the housing 84 topositions above the bottom portion of the chamber body 12. The firstelectrical connectors 86 are arranged at equal intervals around the axisAX. In one example, the number of the first electrical connectors 86 issix. Each of the first electrical connectors 86 has several terminals.The wirings 83 are connected to the terminals of the first electricalconnectors 86, respectively. Each of the terminals of the firstelectrical connectors 86 forms a part of a corresponding one of thewirings 72.

Multiple second electrical connectors 87 are provided directly above thefirst electrical connectors 86. In one example, the number of the secondelectrical connectors 87 is six. The second electrical connectors 87 areconnected to the corresponding one of the first electrical connectors86. The terminals of the second electrical connectors 87 are connectedto the terminals of the first electrical connectors 86, respectively. Inother words, each of the terminals of the second electrical connectors87 forms a part of a corresponding one of the wirings 72.

The second electrical connectors 87 are supported by a plurality ofcircuit boards 88, respectively. The circuit boards 88 are providedabove the respective second electrical connectors 87.

Multiple flexible circuit boards 89 extend from the second electricalconnectors 87 to positions below the peripheral portion 52 p of theelectrostatic chuck 52. Each of the flexible circuit boards 89 is, e.g.,a flexible printed circuit board. Each of the flexible circuit boardshas one or more electrical connectors 74 among the electrical connectors74. In one example, each of the flexible circuit boards 89 has twoelectrical connectors 74. Each of the flexible circuit boards 89provides several wirings. The wirings provided by each of the flexiblecircuit boards 89 connect the terminals of the second electricalconnectors 87 to the terminals of the electrical connectors 74. In otherwords, each of the wirings provided by the flexible circuit boards 89forms a part of a corresponding one of the wirings 72.

As described above, each of the wirings 72 extends in the correspondingone of the first electrical connectors 86, the corresponding one of thesecond electrical connectors 87, and the corresponding one of theflexible circuit boards 89. The wirings 72 have substantially the samelength.

Referring back to FIG. 2, the plasma processing apparatus 1 furtherincludes a plurality of additional circuit boards 90. The additionalcircuit boards 90 are provided in the housing 84 to be positioned belowthe coils 80. The additional circuit boards 90 are arranged along theaxial direction Z. Each of the capacitors 82 is provided on any one ofthe circuit boards 90. The capacitors 82 are mounted on the upper andthe lower surfaces of the circuit boards 90. A wiring pattern forconnecting the coil 80 and the capacitor 82 corresponding to each otheris formed on each of the circuit boards 90. By using the circuit boards90, a large number of capacitors 82 can be supported in the housing 84.

In the plasma processing apparatus 1 described above, a plurality ofcoil groups CG, each including two or more coils 80, are arrangedcoaxially to have the common central axis AXC and, thus, the spaceoccupied by the coils 80 constituting the coil groups CG is small. Inaddition, the coil groups CG are arranged to surround the conductor pipe66 and, thus, the cross-sectional area of each coil 80 is large.Accordingly, a required inductance can be obtained even if the coillength of each coil 80 is short.

In one embodiment, each of the wirings 72 extends in the correspondingone of the first electrical connectors 86, the corresponding one of thesecond electrical connectors 87, and the corresponding one of theflexible circuit boards 89. In the present embodiment, it is possible toextend the wirings 72 in the flexible circuit boards 89 such that thelengths of the wirings 72 become substantially the same. In other words,it is possible to set the lengths of the wirings 72 to be substantiallythe same by the layout of the wiring patterns in the flexible circuitboards 89.

Hereinafter, the description will be explained with reference to FIGS.11 and 12 together with FIGS. 1 and 2. FIG. 11 schematically shows theplasma processing apparatus according to one embodiment. FIG. 11 showsthe plasma processing apparatus 1 in which the wirings 83 are extendedfrom the state shown in FIG. 1. FIG. 12 is a cross-sectional view of thewiring of the filter device according to one embodiment.

As shown in FIG. 1 and FIG. 11, the wirings 83 are configured to varytheir lengths in the housing 84. In one embodiment, each of the wirings83 has a first portion 83 a and a second portion 83 b. The first portion83 a extends in the vertical direction (i.e., along the axial directionZ). One end (upper end) of the first portion 83 a is electricallyconnected to a corresponding one of the heaters HT. In one embodiment,one end of the first portion 83 a is electrically connected to aterminal of a corresponding one of the first electrical connectors 86.

The second portion 83 b is electrically connected to one end (lead line80 a) of a corresponding one of the coils 80. In one embodiment, thesecond portion 83 b extends in the vertical direction. The secondportion 83 b is slidably in contact with the first portion 83 a so thatan overlap length OVL between the first portion 83 a and the secondportion 83 b can be varied. The length of each of the wirings 83 in thehousing 84 is indicated by ‘L1+L2−OVL’. L1 indicates the length of thefirst portion 83 a and L2 indicates the length of the second portion 83b. Therefore, the length of each of the wirings 83 can be adjusted byadjusting the overlap length OVL.

In one embodiment, as shown in FIG. 12, the first portion 83 a is formedin a cylindrical shape. The second portion 83 b can be inserted into thefirst portion 83 a. The second portion 83 b is formed in, e.g., a rodshape. In the present embodiment, the overlap length OVL is an insertionlength of the second portion 83 b inserted into the first portion 83 a.In other words, the length of each of the wirings 83 can be adjusted byadjusting the insertion length of the second portion 83 b inserted intothe first portion 83 a.

In each filter FT of the filter device FD, as the length of the wiring83 connected to the coil 80 in the housing 84 is increased, ahigher-order peak frequency in the frequency characteristic of theimpedance is shifted to a lower frequency side. This is because theelectrostatic capacity between the wiring 83 and the housing 84 and theinductance of the wiring 83 are changed as the length of the wiring 83in the housing 84 is changed. In the filter device FD, the lengths ofthe wirings 83 in the housing 84 are individually adjustable(changeable) and, thus, the higher-order peak frequency of each of thewirings 83 can be adjusted by adjusting the lengths of the wirings 83individually in the housing 84. With this configuration of the filterdevice FD, it is possible to adjust the impedance at the desiredfrequency for each of the filters FT by adjusting the higher-order peakfrequency of each of the filters FT.

While various embodiments have been described above, variousmodifications can be made without being limited to the above-describedembodiments. For example, the plasma processing apparatus may be aplasma processing apparatus having any plasma source, such as aninductively coupled plasma processing apparatus, a plasma processingapparatus that generates plasma by using surface waves such asmicrowaves, or the like.

The lengths of the wirings 83 in the housing 84 may be changedcollectively. Alternatively, the lengths of the wirings 83 connected tothe coils 80 of each of the coil groups CG may be changed collectively,and further the lengths of the wirings 83 connected to the coils 80 ofone of the coil groups CG may be changed collectively, independent ofthe coils 80 of another one of the coil groups CG. The wirings 83 mayextend toward the central axis AXC to come together at a region near thecentral axis AXC and may extend upward from the region.

The shapes of the first portion 83 a and the second portion 83 b are notlimited. For example, the first portion 83 a may be formed in a rodshape and the second portion 83 b may be formed in a cylindrical shape.

Hereinafter, a first simulation to a fourth simulation that have beenconducted to evaluate the filter device FD will be described. In thefirst simulation to the fourth simulation, the lengths of the wirings 83in the housing 84 were set to be different from one another and thecombined impedance of the filters FT was obtained. Specifically, thefirst simulation to the fourth simulation were carried out by settingthe lengths of the wirings 83 in the housing 84 to 0 mm, 200 mm, 400 mm,and 600 mm, respectively. The following is description on other settingsfor the first simulation to the fourth simulation.

<Other Settings for First to Fourth Simulations>

-   -   1. Setting of the coil group CG1        -   The number of coils: 8        -   Shape of each coil: 3 mm×0.8 mm flat rectangle        -   Inner diameter of each coil: 131 mm        -   The number of turns of each coil: 11.33        -   Pitch between turns of each coil: 10.2 mm        -   Coil length of each coil: 115.5 mm        -   Distance between turns of adjacent coils: 2.2 mm        -   Electrostatic capacitance of capacitor connected to each            coil of coil group CG1: 2700 pF    -   2. Setting of the coil group CG2        -   The number of coils: 9        -   Shape of each coil: 3 mm×0.8 mm flat rectangle        -   Inner diameter of each coil: 140 mm        -   The number of turns of each coil: 10.66        -   Pitch between turns of each coil: 10.7 mm        -   Coil length of each coil: 114.1 mm        -   Distance between turns of adjacent coils: 1.7 mm        -   Electrostatic capacitance of capacitor connected to each            coil of coil group CG2: 2700 pF    -   3. Setting of the coil group CG3        -   The number of coils: 9        -   Shape of each coil: 3 mm×0.8 mm flat rectangle        -   Inner diameter of each coil: 149 mm        -   The number of turns of each coil: 10.16        -   Pitch between turns of each coil: 11.3 mm        -   Coil length of each coil: 114.8 mm        -   Distance between turns of adjacent coils: 2.3 mm        -   Electrostatic capacitance of capacitor connected to each            coil of coil group CG3: 2700 pF    -   4. Setting of the coil group CG4        -   The number of coils: 10        -   Shape of each coil: 3 mm×0.8 mm flat rectangle        -   Inner diameter of each coil: 158 mm        -   The number of turns of each coil: 9.66        -   Pitch between turns of each coil: 11.8 mm        -   Coil length of each coil: 113.9 mm        -   Distance between turns of adjacent coils: 1.8 mm        -   Electrostatic capacitance of capacitor connected to each            coil of coil group CG4: 2700 pF    -   5. Setting of the coil group CG5        -   The number of coils: 11        -   Shape of each coil: 3 mm×0.8 mm flat rectangle        -   Inner diameter of each coil: 167 mm        -   The number of turns of each coil: 9.33        -   Pitch between turns of each coil: 12.5 mm        -   Coil length of each coil: 116.6 mm        -   Distance between turns of adjacent coils: 1.5 mm        -   Electrostatic capacitance of capacitor connected to each            coil of coil group CG5: 2700 pF

FIG. 13A is a graph showing the frequency characteristic of theimpedance obtained in the first simulation and the second simulation.FIG. 13B is a graph showing the frequency characteristic of theimpedance obtained in the first simulation and the third simulation.FIG. 13C is a graph showing the frequency characteristic of theimpedance obtained in the first simulation and the fourth simulation. InFIGS. 13A to 13C, the horizontal axis represents the frequency and thevertical axis represents the combined impedance of the filters FT. Ascan be seen from FIG. 13A to 13C, as the lengths of the wirings 83 inthe housing 84 are increased, the higher-order peak frequency is shiftedto the lower frequency side. Therefore, the impedance at the desiredfrequency of each filter FT can be adjusted by adjusting the lengths ofthe wirings 83 in the housing 84.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made departing from the spirit of the disclosures. Theaccompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

1. A filter device comprising: a plurality of coils arranged coaxially;a plurality of wirings, each of which is electrically connected to oneend of each of the coils; a plurality of capacitors, each of which isconnected between the other end of each of the coils and the ground; anda housing electrically grounded and configured to accommodate thereinthe coils, wherein each of the wirings at least partially extends intothe housing and has a length that is adjustable in the housing.
 2. Thefilter device of claim 1, wherein the coils form a plurality of coilgroups, each of the coil groups including two or more coils; in each ofthe coil groups, the two or more coils are arranged such that windingportions of the two or more coils extend in a spiral shape around acentral axis and turns of the winding portions are arranged sequentiallyand repeatedly an axial direction which the central axis extends; andthe coil groups are arranged coaxially with the central axis.
 3. Thefilter device of claim 2, wherein each of the wirings includes: a firstportion; and a second portion electrically connected to one end of acorresponding one of the coils, wherein the second portion is slidablyin contact with the first portion such that an overlap length betweenthe first portion and the second portion is adjustable.
 4. The filterdevice of claim 3, wherein the first portion is formed in a cylindricalshape, the second portion is insertable into the first portion, and theoverlap length is an insertion length of the second portion insertedinto the first portion.
 5. A plasma processing apparatus comprising: achamber; a supporting table configured to support a substrate in aninner space of the chamber, the supporting table including a lowerelectrode and an electrostatic chuck provided on the lower electrode andhaving therein a plurality of heaters; a power feeding unit electricallyconnected to the lower electrode and extending downward from the lowerelectrode; a conductor pipe that is grounded and extends to surround thepower feeding unit outside the chamber; a high frequency power sourceelectrically connected to the power feeding unit; and the filter deviceof claim 1 that is configured to prevent a high frequency power fromflowing into a heater controller from the heaters, wherein each of thewirings of the filter device connects each of the coils with each of theheaters.
 6. The plasma processing apparatus of claim 5, wherein thecoils form a plurality of coil groups, each of the coil groups includingtwo or more coils, in each of the coil groups, the two or more coils arearranged such that winding portions of the two or more coils extend in aspiral shape around a central axis and turns of the winding portions arearranged sequentially and repeatedly in an axial direction in which thecentral axis extends, and the coil groups are arranged coaxially withthe central axis.
 7. The plasma processing apparatus of claim 6, whereineach of the wirings includes: a first portion; and a second portionelectrically connected to one end of a corresponding one of the coils,wherein the second portion is slidably in contact with the first portionsuch that an overlap length between the first portion and the secondportion is adjustable.
 8. The plasma processing apparatus of claim 7,wherein the first portion is formed in a cylindrical shape, the secondportion is insertable into the first portion, and the overlap length isan insertion length of the second portion inserted into the firstportion.